Method of making thermopiles of foil

ABSTRACT

A method of making a thermopile in which a sheet of foil of one material is connected to a sheet of foil of another material so that these sheets are placed at both sides of a line of their connection thus forming a plate; next, apertures are cut in this plate which terminate in slots at two diagonally opposite angles so that two plates with thermocouples, formed by the partitions between the apertures are obtained, which plates are then piled up in such a manner that the sheet of foil of one material of one plate adjoins the sheet of foil of another material of the other plate and the slots in both plates coincide; the two plates are connected within the zone of the slots whose width is equal to the gap between the thermocouples; plates are attached to a framework and the ends of the sheels are cut off beyond the places of their connection, thereby obtaining a thermopile of a number of series connected thermocouples.

United States Patent 1 [111 3,751,798

Altshuler 1 Aug. 14, 1973 METHOD OF MAKING THERMOPILES 0F [57] ABSTRACT v FOIL [76] Inventor: Yakov Avramovich Altshuler, ulitsa A method of making a themmpile in which a Sheet of Bokovaya Veresaeva 5, kv. 3, Lvov, foil of one material is connected to a sheet of foil of an- U.S.S.R. other material so that these sheets are placed at both sides of a line of their connection thus forming a plate; [22] 1972 next, apertures are cut in this plate which terminate in [21] Appl. No.: 228,589 slots at two diagonally opposite angles so that two plates with thermocouples, formed by the partitions between the apertures are obtained, which plates are then [22] $5.3]. piled up in such a manner that the Sheet of foil of one 'fi 3 material of one plate adjoins the sheet of foil of another [5 e o are /57 material of the other plate and the slots in both plates i coincide; the two plates are connected within the zone [56] References C M of the slots whose width is equal to the gap between the UNITED STATES PATENTS thermocouples; plates are attached to a framework and 2,278,744 4/1942 Sparrow et al 29/573 the ends of the sheels are cut off beyond the places of 2,381,819 /1 G a e al 29/573 their connection, thereby obtaining a thermopile of a 3 number of series connected thermocouples. Ll 1 Primary Examiner-Charles W. Lanham Assistant ExaminerW. Tupman Attorney-Holman & Stern I 6 Claims, 4 Drawing Figures I77 J1; /4 a%/ b-s 5 I j d 4 4 5 4 Z. g z i i z 5-- 2 g 3 5... t E S 6 Q I i @R i o j \\Q 1 2 PATENTED M973. 3.751.798

SHEEI 1 or 2 METHOD OF MAKING THERMOPILES OF FOIL BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates to methods of measuring temperature and, more particularly, to a method of making thermopiles of foil and can be used, for example, for producing sensing elements of radiation pyrometers, microcalorimeters, super high frequency power meters, hot-wire electrical measuring instruments, heat flux meters of various meteorological instruments, for example pyranometers, etc.

2. Description of Prior Art Known in the art is a method of making thermopiles in which two rods made of thermoelectrode materials are butt joined, rolled along the junction and the obtained plate consisting of afoil of the two materials is used as a blank for cutting and forming, separate thermocouples which are then secured on a framework in a required order and are connected in series into a thermopile.

However, the above-mentioned method suffers the following disadvantages:

large consumption of labour and high percentage of rejects during the rolling of the joined rods into foil;

erosion of the junction line which makes difficult the manufacture of miniature thermopiles;

difficulties associated with therolling of foil due to different mechanical properties of the joined materials. The conditions of rolling and heat treatment must be different for each material, therefore, during their simultaneous treatment one of the materials is corrugated;

high consumption of labour in making miniature thermopiles, for example for radiation receivers, where some thermocouples have a width within the range of 0.15-0.20 mm while the gap between the thermocouples is 0.1 mm wide. Cutting of such strips, positioning and fixing of each strip on a framework at a distance of 0.1 mm from the adjacent strip and series connection of the thermocouples is a laborious and intricate work.

Consequently, the known method can be employed only for making individual thermopiles and is not suitable for mass production.

SUMMARY OFTHE INVENTION An object of the present invention is to avoid these disadvantages.

The specific object of thejnvention, is to provide such a method of making thermocouples of foil that makes it possible to considerably simplify the'process of their manufacture and to increase the number of thermocouples in a thermopile.

This object is attained by providing a method of making a thermopile in which thethermocouples are made of foils of two different materials and are fixed to a framework; according to the invention, the method comprises the steps of connecting the foil of one material to the foil of another material in such a way that these sheets are positioned at both sides of the line of their connection and form a plate; cutting apertures in this plate which terminate in slots from two diagonally opposite angles, the partitions between the apertures forming a row of thermocouples; placing the two plates obtained thereby, and having thermocouples one upon the other so that the sheet of foil of one material of one plate adjoins the sheet of foil of another material of the other plate; arranging the thermocouples of one plate in the apertures of the other plate in such a manner that the slots of both plates coincide; joining the two plates within the zone of the slots whose width is equal to the gap between the thermocouples; attaching the plates to a framework and cutting off the sheet ends beyond the places of their connection so that a thermopile is ob tained which consists of a number of series-connected thermocouples.

This simplifies the process of making a thermopile using foil, in which separate thermocouples are preliminarily oriented relative to each other and are connected in required order and quantity.

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understood from the following description of one particular embodiment of the invention, reference being made to the accompanying drawings, in which:

FIG. 1 shows a perforated plate for a thermopile of foil manufactured according to the of the present invention method;

FIG. 2 shows two plates made according to the method of the invention and placed one upon the other;

FIG. 3 shows a blank of a thermopile composed of plates provided with apertures and slots according to the method of the invention, and

FIG. 4 shows a thermopile made according to the method of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT The method of making a thermopile according to the invention is effected asfollows.

Two sheets 1 and 2 (FIG. 1) of foil of different thermoelectrode materials, for example chromel and coppel, are joined into a plate in which the-sheets l and 2 are disposed at both sides of their junction line 3. Such connection of the sheets 1 and 2 can be effected by butt or scarf seam welding.

The plate so obtained is provided with a number of apertures 4 so that the partitions 5 between the apertures 4 intersect the junction line 3 of foil sheets I and 2. These partitions serve as thermocouples since they contain junctions of two thermoelectrode materials. The apertures 4 may be of a different shape: rectangular, oval or: circular, but their width must exceed that of the partition 5 therebetween. The apertures 4 are so located that the junction line 3 of the foil sheets 1 and 2 may either be in the medium portion of the partition 5 between the apertures or be displaced towards an end of the partition 5; the line 3 may intersect the partitions 5 at right angles or any convenient angle depending on the required disposition of the junctions in the thermopile.

The plates thus obtained with thermocouples 5 are piled up so that the foil sheet 1 of one material of one plate adjoins in apposition the foil sheet 2 of another material of the other plate, while the thermocouples 5 of one plate are arranged staggered to lie within the ap? ertures 4 of the other plate as shown in FIG. 2.

Then the plates are joined at places close to the ends of the thermocouples 5, for example along the line I, thereby obtaining a double-layer blank. Such blanks are preferably made with a number of thermocouples 5 exceeding that needed for a single thermopile. In this case a portion containing a required number of thermocouples is cut off from the blank, and two oppositesign ends of the extreme thermocouples 5 are connected to terminals serving for inserting the thermopile into a measuring circuit (not shown).

After that, the blank for a single thermopile with terminals is fixed, by methods such as gluing, to a framework (not shown) with a dielectric surface, for example shaped as a flat frame. The blank is arranged on the framework so that the working junctions of the thermocouples 5 located on the partitions of the apertures occur in its medium portion and have no contact with the framework while the ends of the thermocouples adjoin the frame of the framework. Then the adjacent thermocouples are disconnected in such a manner that only series connections remain between the thermocouples. This can be effected, for example, by removing the material along the lines II.

This succession of operations is applicable for the plates having any form configuration of apertures. When a thermopile must meet the requirements of miniaturization, and requirements of maximum radiation of its receiving surface and minimum distance between its thermocouples, the apertures are preferably made in the form of elongated rectangles 6 (FIG. 3) featuring narrow slots 7 at diagonally opposite ends thereof. In this case the distance between the apertures 4 is equal to the width of a separate thermocouple 5, while the width of the aperture 4, 6 is equal to that of a single thermocouple 5 and two gaps between the thermocouples 5 in the thermopile.

In the foil sheet, in which there are made rectangular apertures 6 having extending narrow slots 7, a row of thermocuples 5 is formed with rectangular widenings at the ends, in which case the thermocouples in their middle portion are divided by the rectangular apertures 6 and at the ends are divided by the slots 7.

The plates with such apertures 6 are piled up so that the thermocouples 5 of one plate are disposed in the apertures 6 of the other plate, while the slots 7 of both plates coincide; the plates are connected to each other and attached to the framework 8 (FIG. 4) as described above. The disconnection of the thermocouples of the blank attached to the framework 8 in this case is substantially simplified. For this purpose it is sufficient to cut off the edges of the blank along the line III (FIG. 3) intersecting the slots 7.

The present method makes it possible to vary the position of the working layers of the thermopile and this is very important in designing special radiation pyrometers. For example, for filamentous objects the junctions are preferably disposed along a straight line, and for other applications it is necessary to provide for uniform distribution of the sensitivity of the thermopile over its receiving area.

This is obtained by selecting the level and inclination of the plane of intersection of the apertures 4, 6 of the junction lines.

At mutual intersection of the junction lines and the partitions at a right angle, the junctions of the themepile are disposed along the line passing through the middle of the receiving surface of the thermopile. If the line of the junctions passes at a right angle to the partitions 5 between the apertures 4, 6, and yet is displaced relative to the centre of the length of the thermocouple 5, the junctions of the thermopile are arranged in two parallel rows.

It the partitions 5 between the apertures 4, 6 intersect the junction line at another angle, the thermopile junctions are disposed along two inclined lines.

The use of the finished foil of each material provides for a better stability of properties of a thermopile and high efficiency of the process of its manufacture as well as for obtaining sharply defined junctions of the thermocouples.

Owing to the fact that in each plate separate thermocouples are preliminary oriented relative to each other, the piling up of two plates and coincidence of the slots 7 ensure the orientation of all the thermocouples of the thermopile and their positioning with the required gaps. The proposed method enables most of the labourconsuming operations to be excluded from the process of making thermopiles. The connection of separate thermocouples into a thermopile is also facilitated since it can be effected by means of seam welding of a large number of cold junctions of thermocouples at a time.

Since all thermocouples are made of a single plate and are coupled thereto prior to fixing them on a framework, their deformation and twisting are eliminated, which otherwise would make working with miniature strips of thin foil extremely difficult. Due to a substantially improved strength of the plate compared with a conventional prior art thermocouple, the thinnest materials (of 1 micron and thinner) can be used and this makes it possible to increase the sensitivity and response of the thermopiles serving as radiation receivers.

The thermopiles produced by the proposed method have still another advantage consisting in that their cold junctions may have a mass and surface considerably exceeding those of hot junctions thereby permitting heat conduction from the cold layers to the housing to be improved, and this is extemely important for compensating for the effect of the ambient medium temperature.

What is claimed is:

l. A method of making a thermopile comprising the steps of joining a first sheet of foil of one material to a second sheet'of foil of another material in a common plane in such a way that said sheets are disposed at both sides of a line of their junction, thereby forming a plate, cutting a series of apertures spaced by partitions in said plate, and forming terminals in slots at two diagonally opposite comers of the apertures, while partitions between said apertures form thermocouples of said thermopile; placing two of said plates obtained thereby and superposing said thermocouples one upon the other in such a manner that said first sheet of foil of one plate adjoins said second sheet of foil of the other plate; staggeringly disposing said thermocouples of said one plate within said apertures of said other plate so that said slots of apertures in both said plates coincide; joining both said plates within a zone of said slots; attaching both said joined plates to a framework and cutting off the ends of said sheets beyond the places of their junction, thereby obtaining said thermopile formed by a number of series-connected thermocouples.

2. A method as of claim 1 wherein the step of cutting a series of apertures comprises cutting a series of elongated rectangles perpendicular to said line of junction of the sheets.

a series of apertures comprises cutting elongated rectangles of width greater than said partitions.

6. A method as of claim I wherein the step of cutting a series of apertures comprises cutting aligned slots, the length of which is symmetrical about said line of junction. 

1. A method of making a thermopile comprising the steps of joining a first sheet of foil of one material to a second sheet of foil of another material in a common plane in such a way that said sheets are disposed at both sides of a line of their junction, thereby forming a plate, cutting a series of apertures spaced by partitions in said plate, and forming terminals in slots at two diagonally opposite corners of the apertures, while partitions between said apertures form thermocouples of said thermopile; placing two of said plates obtained thereby and superposing said thermocouples one upon the other in such a manner that said first sheet of foil of one plate adjoins said second sheet of foil of the other plate; staggeringly disposing said thermocouples of said one plate within said apertures of said other plate so that said slots of apertures in both said plates coincide; joining both said plates within a zone of said slots; attaching both said joined plates to a framework and cutting off the ends of said sheets beyond the places of their junction, thereby obtaining said thermopile formed by a number of series-connected thermocouples.
 2. A method as of claim 1 wherein the step of cutting a series of apertures comprises cutting a series of elongated rectangles perpendicular to said line of junction of the sheets.
 3. A method as of claim 1 wherein the step of joining said first sheet of foil with said second sheet of foil comprises joining by scarf seam welding.
 4. A method as of claim 1 wherein the step of joining said first sheet of foil with said second sheet of foil comprises joining by butt welding.
 5. A method as of claim 1 wherein the step of cutting a series of apertures comprises cutting elongated rectangles of width greater than said partitions.
 6. A method as of claim 1 wherein the step of cutting a series of apertures comprises cutting aligned slots, the length of which is symmetrical about said line of junction. 